Table 5.
Summary of human studies involving different diets and their effects on the gut microbiota.
| References | Study Design, Sample, Follow-up | Intervention | Results |
|---|---|---|---|
| CKD patients | |||
| Marzocco et al., 2013 [95] | RCT with crossover; 32 non-dialysis CKD patients; 1 week | VLPD (0.3 g/kg bw/day) + ketoanalogues LPD (0.6 g/kg bw/day) |
VLPD changed the IS level with a reduction of 37% when compared to LPD |
| Kandouz et al., 2016 [99] | Cross-sectional; 138 HD patients from a cohort were analyzed and 16 patients were strict vegetarians | Vegetarian diet | ↓ IS and p-CS levels; ↓ serum urea, and phosphate and estimated urea nitrogen intake before HD |
| Black et al., 2018 [20] | Longitudinal; 30 non-dialysis CKD patients; 6 months | LPD (0.6 g/kg/day) | ↓ p-CS plasma levels Change in the intestinal microbiota profile ↔ IS, IAA |
| Mafra et al, 2018 [101] | Prospective pilot study; 9 non-dialysis CKD patients; 6 months | LPD (0.6 g protein/kg day) | ↓ TMAO plasma levels |
| Patel et al., 2012 [100] | 15 healthy vegetarian individuals 11 health individuals – normal diet |
Vegetarian diet | ↓ p-CS and IS production rates |
| Non CKD patients | |||
| De Filippis et al, 2016 [108] | Cross-sectional survey; 51 vegetarians, 51 vegans, 51 omnivores |
Adherence to the Mediterranean diet | Associations between consumption of vegetable-based diets and higher levels of short-chain fecal fatty acids, Prevotella and fiber-degrading Firmicutes; ↓ urinary TMAO levels in vegetarian and vegan diet |
| Mitsou et al, 2017 [109] | Cross-sectional study, 120 healthy participants | Adherence to the Mediterranean diet | ↓ Escherichia Coli counts, ↑ Bifidobacteria |
| Garcia-Mantrana et al, 2018 [96] | Cross-sectional study; 27 healthy volunteers | Adherence to the Mediterranean diet | ↑ Bifidobacterial counts, ↑ concentration of acetate, propionate, and butyrate in fecal samples, ↑ Bacteroidetes and a lower Firmicutes–Bacteroidetes ratio |
Abbreviations: VLPD: very low-protein diet; LPD: Low-protein diet; p-CS: p-cresyl sulfate; IS: indoxyl sulfate; IAA: indole-3-acetic acid; TMAO: trimethylamine-N-oxide; CKD: chronic kidney disease; HD: hemodialysis; ↔: no change; ↑: increase; ↓: decrease.